1. Field of the Invention
The present invention relates to a visual target apparatus used in ophthalmic instruments such as an eye-refractometer and an optometer.
2. Related Background Art
In a visual target system in a conventional eye-refractometer, a visual target is presented by illuminating a slide film with a figure or image from behind the slide film. A facade or apparent diopter of the visual target is changed by moving an optical member. In this case, since the facade or apparent size of the visual target is not almost changed, it is therefore difficult to express a remote feeling to the visual target. More specifically, when the diopter of the visual target is gradually increased in order to guide the eye to a point at a far distance, if the size of the visual target is not sufficiently decreased, the visual target does not appear to naturally move toward a point at far distance. When such an visual target system is also employed in a eyesight test, a BADAL optical system in which the facade size of the visual target is not changed with the diopter is employed. Since the size of the visual target is not changed in this BADAL optical system, it is not suitable for inducing accommodation. Note that even if the visual target system is used in only eyesight tests, not to change the facade size of the visual target in a conventional system, a special optical system called a BADAL optical system is required.